Engine starter drive



iA n'l 27,1948. D. L. MILLER 2,440,657

' ENGINE STARTER DRIVE Filed Feb. 25,1946

INVENTQR.

3 .2 i mm.-

Patented Apr. 27, 1948 ENGINE s'ran'rnn DRIVE Donald L. Miller, Pine City, N. in, minor to Bendix Aviation Corporation, Elmira Heights, N. Y., a corporation of Delaware Application February 25, 1946, Serial No. 649,999

' Claims. (cl. "ii-"1) I l The present invention relates to an engine starter drive and more particularly to starter gearing which is adapted to be used interchange ably with various types of installation. 7

Space and design requirements of various internal combustion engine power units sometimes require that the starter pinion shall move away from the starting motor and sometimes that the pinion move toward the motor, in order to engage the engine gear. The first type of drive is desiggearing is shown as an outboard drive mounted on a uniform diametered power shaft I which may be the armature shaft of an electric motor 2. The outer end of the shaft is supported by a bearing 3 on the extension 4 of the casing of motor 2. A power transmission member in the form of a drive head 5 is fixed to said shaft by any suitable means such as a drive pin 6 traversing both the head and the shaft and retained nated the "outboard type and the second the inboard type, and heretofore these types have 7 "of the pinion to pump or back out of mesh during cranking, and to rebound toward the engine gear after being thrown out of mesh when the engine starts.

It is a further object to provide such a device in which the actuating means comprises two parts with an overrunning clutch connecting the parts.

'It is a further object to provide such a device in which a single spring is used to assist in returning the parts of the starter drive to idle position, to prevent drifting of the engine driving member from idle position, and also to close the clutch between the parts of the actuating means.

Further objects and advantages will be apparcut tothose skilled in the art 'by reference to the specification and the accompanying drawing, in which:

Fig. 1 is a side elevation partly in section of a preferred form of the invention showing the parts parts thereof in idle position; v

Fig. 2 is 'a perspective view of the parts on which the overrunning clutch is formed; and

Fig. 3 is a side elevation partly in section of an inboard type of drive embodying the present invention, the parts being shown in cranking position.

In Fig. 1 of the drawing, the engine starter therein by a ring 1 seated against a shoulder 8 on the drive head 5. An actuating member in .the form of a screw shaft 9, having threads I0,

is slidably journaled on the power shaft I adjacent the drive head 5, and a control member in the form of a nut II is threaded on the screw shaft. Closely adjacent the forward end of the screw shaft 9, an engine driving member in the form of a pinion I2 is slidably journalled on power shaft I in position to engage and rotate an engine member such as a gear I3. The pinion I2 has aradial flange I4 fixed thereto 'by any suitable means such as upsetting at I5, and a thimble I6 is held onto the flange by suitable meanssuch as welding at IT. The axial extention of thimble I5 telescopes over the control nut to form a sliding joint. I

Resilient means are provided for operatively connecting the pinion to the control nut includingv a ring I9 of yieldable material such as rubber seated on the control nut against a radial flange I8, and bearing frictionally on the thimble I6.

Unitary means for uniting and enclosing the parts of the drive and for positively limiting the meshing movement of the pinion is provided in the form of a casing member 2| havingan annular recess 22 in which the flange I I and thimble I6 are fixedly retained by any suitable means such. as crimping as indicated at 23. An interior shoulder 24 is provided in casing 2|, forming an abutment for the control nut flange I8 which is so located as to compress the rubber ring I9" slightly when the crimping operation at 23 is completed. In order to define the meshing position of the pinion I2, the casing 2| is provided with an extension 21 which terminates in a radial wall 28 closely surrounding the shaft I and adapted to abut against the drive head 5 when the pinion I2 is fully meshed with the engine gear I3. The extension 21 of casing 2| is preferably tapered as illustrated so as to enable it to extend I 3 into theinterior-of the motor 2, thus reducing the overall length of the drive. The rearward or idle position of the pinion is defined by the engagement of the thread ends on the control nut against thread run-outs 28 On the screw shaft 9, the threads ill being terminated short of the end of the screw shaft as shown in Fig. 2.

An overrunning clutch is provided between the drive head 5 and screw shaft 9 in the form of ratchet teeth 29 and 3| on the adjacent radial surfaces of the head and screw shaft respectively. The teeth 29 and 3| are normally held in engagement by a compression spring 32 seated at its rear end against the wall 26 and at the forward end against the flanged ring I. Spring 82 also serves as illustrated tables the casing 2| and pinion l2 toward idle position, and thereby prevent the pinion from drifting into undesired engagement with the engine gear. 21 is provided with an opening 33 permitting insertion or withdrawal of the pin 6 after the ring 1 has been moved back out of the way by a suitable tool inserted through said opening. The opening may be closed by a suitable cover or plug if it be desired to completely' enclose the working parts of the drive.

In assembling, the starting drive is first put together on a dummy'shaft without using the drive pin 6. The first step is to place the casing 2| over the dummy shaft and then place the spring 32 against wall 26 within the casing, followed by the ring 1 and head 5. A sub-assembly is then put together by screwing the control nut over the shaft 9, placing the rubber ring I9 over the control nut and seating the pinion member in place against ring I9. The sub-assembly is then slid over the dummy shaft toward the casing until the control nut flange 8 rests against the casing shoulder 24 and the fiange ll enters the recess 22. Next, the casing, having the parts assembled therein, is placed in a powered crimping machine and the lip 23 is bent tightly over the periphery of the pinion flange. The ring I is,

then pushed back by a suitable tool such as a screw driver and the pin 6 entered into the opening in head 5, whereupon the drive is ready for installation on a starting motor. This operation is accomplished by withdrawing the dummy shaft, sliding the drive on the power shaft until the pin 6 lines up with the opening in the shaft,

and then looking the drive on the shaft by pressing in the pin until it is flush with the drive head 5. The tool used to hold the ring I in backward position is then removed allowing the ring to snap forward and lock the drive pin 6 in place.

In operation, upon energization of the starting motor, the normally closed clutch 29, 3| transmits rotation from the shaft I and .head 5 to the screw shaft 9 while the control nut II and its associated parts by reason of their inertia do not retate but traverse longitudinally along the shaft until the pinion I2 is in full mesh with the gear IS. The wall 26 of easing 2| then engages the rear face of the head 5 and stops the forward traversal of the pinion. Further rotation of the motor shaft istransmitted yieldably to the pinion through compression and torsion of the yielding element l9. Whenthe engine starts, the

acceleration ofthe engine gear |3 causes the nut member II to overrun the motor shaft thereby threading the control nut back on the screw shaft 9 and allowing the spring 32 to draw the pinion l2 back to idle position. As the control nut reaches idle position it engages the ends 28 of the threads on the screw shaft 3 and transmits The extension 4 its rotative speed to the screw shaft, causing the ratchet clutch 29, 3| to overrun, thus dissipating the energy of the rotating parts without causing rebounding of the pinion toward the engine gear. The spring 32 thereafter holds the clutch closed and the pinion l2 in idle position.

In Fig. 3 of the drawing, there is illustrated an example of the present invention used as an "inboard drive, in which the pinion moves toward the starting motor as it meshes with the engine gear. The anchorage of the drive to the armature shaft is in this case adjacent the outer end of the shaft, and the drive faces toward the motor, but the parts are otherwise the same as in the embodiment first disclosed, and further description thereof is deemed unnecessary.

Although certain structure has been shown and described in detail, it will be understood that other embodiments are possible and changes may be made in the form and arrangement of the parts without departing from the spirit of the invention.

What is claimed is:

1. In an engine starter drive, a power shaft, a drive head fixed thereon, a screw shaft slidably joumalled on said power shaft in tandem relation with said head, said head and screw shaft having interengaging means forming an overa running clutch connection therebetween, a control nut threaded on said screw shaft, said screw shaft having an abutment for positioning said nut thereon when in idle position, a pinion slidably journalled on said power shaft to-engage and rotate a. gear on an engine to be started, and means for driving said pinion from said nut and for closing said clutch including a casing member fixed to the pinion and a resilient member yieldingly transmitting torque from the nut to the casing.

2. In an engine starter drive, a motor shaft having a uniform diameter throughout its length. a drive head fixed on said motor shaft and having a shoulder thereon, a screw shaft slidably joumalled on said motor shaft adjacent said drive head, said head and screw shaft having interengaging means constituting an overrunning clutch therebetween, a control nut threaded on said screw shaft having a radial flange and a resilient member mounted on said nut, a casing surrounding the nut and screw shaft having a rearwardly extending portion terminating in a radial wall, a pinion having a flange fixed to the front end of the casing slidably journalled on said motor shaft for traversal into engagement with an engine gear, a resilient member located between the flanges of the nut and pinion for rotating said pinion from said control nut, and unitary elastic means bearing against said radial wall and said shoulder on the drive head for urging said pinion toward demeshed position and for holding said clutch closed.

3. An engine starter drive as set forth in claim 2 in which the terminal flange of the casing is arranged to abut against the rear face of the drive head to limit the traversal of the casing and thereby define positively the meshed position of the pinion and at the same time force said clutch elements together.

4. In an engine starter drive, a power shaft, a driving head fixed thereon, a screw shaft having a disconnectable torque transmitting connection to the driving head, a pinion slidably journalled on the power shaft, 8. control nut threaded on the screw shaft, a yielding driving connection between the control nut and pinion including a casing an extension enclosing the driving head and providing an abutment adapted to engage the drivin'g head and thereby limit the longitudinal movement of the pinion, and cause the screw shaft to be pressed by its end thrust against the adjacent face of the drive head. i

5. An engine starter drive as set forth in claim 4 including further, a, compression spring located between the drive head and the abutment on the casing member for urging the casing and pinion 0 toward idle position, said screw shaft having an I abutment thereon for limiting the rearward travel REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,313,656 Martin Mar. 9. i943 

